Flyash Pond Issues were tackled in the Hot Topic Hour on February 19th
High quality presentations and good questions provided insights into the type of problem which TVA encountered and provided approaches for avoiding repetition. There was agreement that the contamination was greatly exaggerated but that it would result in regulations which will impact many utilities.
Ari Lewis, manager of the Toxicology Team at Gradient Corporation, explained why it is inappropriate to conclude that a substance such as coal ash is toxic without an underlying risk analysis. She emphasized that the dosage is critical. Arsenic is found in food and in the ground in small quantities and is not a problem. On the other hand 100 aspirins is life threatening. In general coal as-is is not a concern from a risk assessment.
Jim Johnson, Golder Associates, described a process for removing the water from flyash and turning it into a stable solid paste at the Montana Colstrip plant. This process eliminated seepage and will greatly increase the life of the impoundment.
Jim Hill, Senior Vice President Arcadis U.S., discussed the risk factors associated with flyash ponds and the issues that should be considered when designing containment ponds to eliminate or minimize these risks. One of the challenges is that new air pollution control schemes will enrich the heavy metals in the ash.
David Goss, Executive Director American Coal Ash Association, spoke about the challenges facing the utility industry regarding Coal Combustion Byproducts (CCP’s) and the beneficial uses of CCP and FGD byproducts. The press provided distorted coverage of the TVA spill using words such as “toxic sludge.” It was reported that there were 1,300 similar sites when in fact the site is unique and there are less than 200 wet impoundment ponds. On the other hand, the dry option has maintenance and other advantages.
Mike Ruetten, Principal Engineer AECOM, discussed the risk factors related to containment ponds. Routine inspections are generally conducted weekly. A failure mode analysis is warranted periodically where types of failure modes and level of risk are determined and action items are defined.
Bios, Photos and Abstracts can be accessed at February 19, 2009 Bios, Photos and Abstracts - Hot Topic Hour.htm
The individual power points are in the Particulate Decision Tree and can be viewed as follows:
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Pond Issues |
Particulate Continuing Decision Process For: Pond Issues
The following presentations are from the Flyash Pond Issues Hot Topic Hour February 19, 2009.
Is Coal Toxic? Presented by Ari Lewis, Gradient Corporation.
Coal Ash Impoundments Background and Why are they Used? Presented by David Goss, American Coal Ash Association
Paste Flyash Management to Reduce Seepage and Minimize future Dam Construction at PPL Montana's Colstrip SES. Presented by James M. Johnson, Golder Associates
Increased Emphasis on Groundwater Issues? Presented by Jim Hill, Arcadis
Geotechnical Risk Assessment of Existing Ash Disposal Facilities. Presented by Michael Ruetten, AECOM